This invention relates to retaining contacts in the housing of electrical connectors and in particular to retaining very close center line spacing contacts in the housing of an electrical connector utilizing asymmetric retention features of the contact cooperating with structure of the housing.
As the down sizing of electronic devices has progressed, more contacts are placed in smaller and smaller connectors to consume less space. As the density of contacts in connectors increases, the center line spacing between contacts has decreased. Due to the higher density closer spacing of contacts, more attention must be given than in the past to the sufficiency of dielectric materials, whether plastic or air, separating the closest portions of adjacent contacts to assure that the contacts can withstand voltage levels sufficient to make the connector of practical use.
Contacts or terminals are pressed or pushed into contact receiving channels or passages during assembly of a connector. The contacts are positioned at a desired location in the channel or passage during manufacture and remain in that position during use of the connector.
Features of the contact typically secure the contact in the passage or channel such as a lance as disclosed in U.S. Pat. Nos. 3,414,871 and 4,726,792. When the contact is secured in a passage or channel by an interference fit, barb features on the contact plow through plastic of the dielectric housing in an interference fit and secure the contact in a passage or channel.
Typically the barb features are spaced symmetrically across the center line axis of the contact and if multiple barb features are present to enhance retention, they are spaced symmetrically across and axially along the contact. U.S. Pat. Nos. 4,775,336 and 4,808,125 disclose typical contact retention features of this type.
Some down sized symmetrical barb retention systems have been problematic in that barbs on opposite sides of a rib of dielectric material separating adjacent contact receiving channels of a dielectric connector housing have so stressed the dielectric material forming the rib that the dielectric material has failed. Sometimes the failure is audible. This failure provides a crack in the dielectric material that would otherwise separate the barbs of adjacent contacts thus changing the dielectric material separating the barbs from the plastic of the housing material to air. This can result in arcing between adjacent contacts through the crack across the resulting short distance of separation.
This type of housing dielectric failure can be affected by the thickness of dielectric material separating contacts, the extent to which barbs extend into the dielectric material, the voltage level of the signal on the contacts, the plastic material from which the connector is molded, and the proper processing of the plastic material such as preventing the plastic from becoming too hot during molding so as not to become brittle.
It would be desirable to have a contact retention system for high density contact spacing that would reduce the stress on the dielectric housing material separating adjacent contact receiving channels as contact receiving channels are positioned more closely together in higher density contact connectors.